Adjustable truss for pistons



Feb. 9, 1937.

Z. A. BRUEGGER ADJUSTABLE TRUSS FOR PISTONS Filed Jan. 31, 1954 I Z-A-B BY 7 MTTORNEVYS 7 Patented Feb. 9, 1937 UNITED STATES PATENT OFFICE ADJUSTABLE TRUSS FOR PISTONS Zeno Arno Bruegger, Boise, Idaho Application January 31, 1934, Serial No. 709,222

15 Claim.

This invention relates to improvements in pistons, and its objects are as follows:-

First, to provide means to make an adjust- .ment compensating for the collapse or wear of the piston skirt and cylinder wall from the top of the piston head without tearing down the engine more than to remove the cylinder head, or through a hole provided in the cylinder head, fitted with a removable plug, through which the adjustment screw is reached.

. Second, to provide any suitable means on the piston head by which to adjust the skirt without removing the piston from the cylinder.

Third, to provide an adjusting device on top of the piston for controllingthe circumferential dimension of the skirt. I I

Fourth, to provide a skirt truss which can be adjusted either from the top or bottom of the piston.

member to ride in the substantially upright slot of the piston skirt for the purpose of guiding the slide member and preventing its shifting sidewise.

the following specification, reference being had to the accompanying drawing in which,

Figure 1 is a vertical cross section of a piston illustrating one means for adjusting the skirt from the top of the piston.

Figure 2 is a side elevation, particularly illustrating the sliding key for keeping the slide member in alignment.

Figure '3 is a perspective view of a truss expander wherein the buffer spring is made separate from the slide member to enable an adjustment of the piston from the bottom as well as the top.

Figure 4 is a front elevation of the buffer spring.

Figure 5 is a perspective view showing the ad- I justable truss made in one piece with the exception of the adjusting screw.

Figure 6 is a detail plan view of the piston showing a center punch mark used to hold the setting of the adjusting device.

Figure 7 is a detail section on the line 1-1 of Figure 3. I I

Figure 8 is a detail view illustrating the hole in the cylinder head, fitted with "a removable plug, through which adjustments of the screw in the piston can be made.

There are on the market a number of devices intended to maintain the diameter of a crushed 55 piston. In some cases these devices are perma- Fifth, to provide at least one key on the slide Other objects and advantages will appearin nently embodied in the piston, in fact embedded in the metal of the piston, while in other cases they are put in place from the bottom or'open end of the skirt. If any adjustment is possible at all in the latter type it is necessary to remove 5 the piston in order to get at the device.

This means taking down the engine, and it is the prevention of that labor which is herein contemplated by the improved skirt adjusten, The instant device is originally fitted inside of the 10 piston. In preferred instances it is adjustable from the-top ofthe head, for ,which purpose it is loosely mounted in the piston. But the device is not loose in the sense of being freely movable during the operation of the piston, the only time 15 that it is capable of movement being when an adjustment is made. In other instances an adjustment can be made from the bottom of the piston as when the engine has been necessarily torn down. i v

Reference is made to the drawing. A piston l of any known type, includes a head 2, skirt 3 and an expansion slot 4. The slotting of the piston as shown in Fig. 2 produces skirt sections which are acted upon by the adjustable truss. The ad- 25 justable truss or skirt adjuster, which comprises the chief invention, consists of, a slide member 5, a member 6, usually, but not necessarily, a

spring, and an adjusting device 1, herein shown as an ordinary fiat-headed machine screw. The 30 member 6, herein variously known as a bufier spring, tension member, truss and an abutment member, may consist of either an actual spring (either leaf or coil) or simply an ordinary piece.

of flat steel disposed on a substantial diagonal 35 across the inside of the piston. The screw goes through a smooth hole 1" in the piston head 2, but the hole is countersunk or socketed to take the beveled under part of the head, thereby to prevent leakage. The spring 6, instead of being 40 a single piece as shown, may consist of two or more leaves overlapped and flexible like the spring of an automobile axle.

' The slide member 5 occupies an upright position inside of the piston, immediately behind 45 the slot 4, against which it is pressed by the spring 6. This member consists of a rigid bar embodying a key 8 which is projected into the slot 4 for the purpose of keeping the member 5 in alignment during its vertical adjustments. 50 7 Figures. 1 and 2 illustrate the use of two such keys, it being a matter of judgment whether or not the extra one is necessary. \7

Many times the expansion slot 5 willbe on a slight slant as shown in Figure 2. The key 8 6.5

as a tendency to twist the slide member 5 with respect to the device 1 when the latter is adjusted. The adjustment is held by making a center punch mark (Fig. 6) in the head of the piston beside the screw head so as to force a little of the head metal into the screw slot. The key 8 is usually an integralpart of the member 5, and according to the showing thereduced end of it is upset in back of the slide member as at 9. But instead of making the key rigid at 9, that point may be converted into a swivel which will allow swivelling of the key'so that .ceives the inner end of the adjusting device I.

,The tension of the spring 6 is always downward and outward (arrows a, b, Fig. 1). The downward tension exercises a constant pull on the device 1, so that the head of' it never leaves the socket in the head 2 of the piston. Clockwise rotation of the device I (looking down on it) draws the adjuster up into the piston and expands the skirts by virtue of decreasing the distance between the anchorage andv abutment points (later described) of the spring 8. Counter-clockwise rotation releases the slide. member for downward movement in the piston, increasing the distance between said point so as to permit the skirt 3- to contract. When a steel bar is used instead of the buffer spring the downward pressure is produced by the inward pressure of the piston skirt sections trying to return to their original set out of which they have been forced by the sliding member.

The lower end of the spring 6 is anchored to the slide member 5 in any one of various ways. In Figure 1 the anchoring is done by fusing at I l. The free end of the spring has an abutment substantially in the corner of the head 2 on the inside. For that purpose the free end is sharpened at I 2 so that it can dig into the metal at i3, usually and most conveniently in the annular internal corner. where the head merges into the skirt.

In Figure 3 the principle of the adjustable truss is identical with that of Figure 1, although the structure is slightly different. Such parts as are alike have the same reference characters with the exponent letters a. The slide member 5 and buffer spring 6 are still separate, but instead of the anchorage ll being rigidly fixed as in Figure l it ismade adjustable by a screw ll or its equivalent.

This screw is driven into a threaded hole in the U-shaped bend H5 at the bottom of the slide member. The lower end of the spring 6' is fitted in the space of the U, and said end has a notch I 6 (Fig. 4) which the notched point ll of the screw enters. The screw ll is prevented from turning by the tension of spring 6 or recoil of piston skirt sections forcing the part l6 into the notch at every one-half revolution of screw. The arm Ill is bent upon itself as at H to provide more thread space for the screw 1. The screw 1* is driven through matching holes both in the arm [0? and the bend l1. v

Figure 4 is a detail view of the bufier spring yThlS particularly illustrates the form of the sharpened end I2 This is a double pronged arrangement which will effectively dig into the metal as already brought out. Any equivalent will been a corresponding slant but fits in the slot rather loosely. This prevents binding between the key and the walls of the slot, as well arrangement can be adopted, the one shown merely being for illustration. This spring like the first one may comprise one or more leaves.

It is not necessary to use a spring (such as 6). to obtain the functioning as set forth. Any

ordinary straight piece of steel placed between points II and I3 would pry the skirt apart in the same manner. A spring is merely used as a bufler or cushion to compensate for any irregularities of cylinder wall.

Figure 5 illustrates a' one-piece. adjuster. That is to say, the slide member 5 and bufier spring 6 are manufactured to form out of one piece of material, the anchorage at H comprising a continuation of one part into the other. The structure at the top of the slide member is identical with that shown in Figure 3, as is also the structure at the top of the buffer spring.

When referring to the adjuster in Figure 5 as a one-piece construction, the slide member andbuffer spring are meant. The top adjusting device is separate. The omission of the key will be noted in Figure 5, as an example.

It has been stated that the truss is the chief invention. The combination of said truss and the piston I is also embraced in the invention. When the truss is once embodied in the piston the head 2 becomes and remains an essential part of it because of the function that it performs as an abutment for the adjusting device I and the free end of the bufier spring 6.

The operation is readily understood. When the piston l becomes too loose in its cylinder the device I is adjusted so as to raise the truss. This adjustment is made by turning the screw 1 clockwise (looking down). This draws the slide member 5 upwardly, thus shortening the distance between the points II, i3. The member thus changes its angularityand presses the slide member 5 harder against the skirt of the piston so that the slot 4 is separated a slightly greater distance than before. This increases the diameter of the skirt. The adjustment is made while the piston is still in the cylinder,

Inasmuch as the sharpened free end of the spring has dug into the head 2 at the point l3 it follows that this is an abutment from which the outward pressure occurs. Should it be desired to make a reverse adjustment, that is to say to permit contraction of the skirt, the screw I would be turned counter-clockwise. The inherent tendency of the spring 6 is to move downwardly in the .general direction of the arrow a (Fig. 1).

The tension of the spring or recoil of the forced piston skirt sections constantly pushes the slide member and so maintains the head of the adjusting device 1 in contact with the top of the piston. This provides the only swivel that is necessary. When the screw is turned counter-clockwise as stated, the slide member will move downwardly, and the free end of the buifer spring will unbend and slip away from the point l3, dragging on the underside of the head, but when an adjustment is made for increasing the diameter the sharpened end l2 will presently return to the point l3 which then resumes its function as an abutment.

Reference has been made before to a hole in the cylinder head through which to reach with a screwdriver (or other implement) for the adjustment of the screw in the piston head. In Figure 8 the engine cylinder and head of any known type are commonly designated It. The head of the cylinder has a hole i9 of a suitable 2,070,197 kind, normally closed by a plug 20, in position to register with the-screw 'l or substantially so. The

plug 20 has only to be removed to gain access to the screw 1 for adjustment as hereinbefore brought out. Were. it not for the fact that the usual spark plug hole comes over to one side and is generally out of registration with the bore said hole could be used for the purpose of reaching through. It is only to make sure of the provision of an opening for access to the adjusting screw that the hole i9 is provided.

1. In a piston having a slotted skirt, expander means inside of-the piston including a bowed bufler spring having one terminal abutting the top and the other terminal adjacent to the skirt, a slide member next to the skirt to which member said other terminal of the spring is anchored, and an adjusting device carried by said slide member and going through the top of the piston, said device being adjustable from the top of the piston for moving the slide member up and down to change the terminal distance of the spring and vary its pressure against the skirt.

2. In a piston having a slotted skirt, expander means inside of the piston including a bowed buffer spring having means at one end enabling it to connect with the piston head to form an abutment, a slide member next to the skirt and means for anchoring the other end of the spring to said slide. member, an arm on the slide member, and an adjusting device attached to the arm and going through the head of the piston, said device being accessible for adjustment with out removing the piston fromthe cylinder to move the slide member up and down.

3. In a piston-having a slotted skirt, expander means inside of the piston including a.bowed buffer spring having means at one end enabling it to connect with the piston head to form an abutment, a slide member next to the skirt and means for anchoring the other end of the spring to said slide member, an arm on the slide member, an adjusting device attached to the arm and going through the head of the piston, said device being accessible for adjustment without removing the piston from the cylinder to move the slide member up and down, and a key on the slide member projecting into the slot of the skirt.

4. In a piston having a slotted skirt, expander means inside of the piston comprising a bufier spring, a slide member next to the skirt, having a U-shaped bend at one end to receive one end of the spring and an arm at the other end, the other end of the spring having means for digging into the piston head to form anzabutment, an adjusting screw threaded into the arm and passing through the head for adjustment from above the head, and an adjusting screw threaded into said bend and contacting the respective end of the spring.

5. In a. piston having a slotted skirt, expander means inside of the piston comprising "a slide member and abutment member in one piece, the slide member having an arm bent upon iisel jrand the abutment member having a sharpened end to dig into the piston head, and a screw threaded through the bent part of the arm and occupying a smooth hole in the piston head.

6. The combination of a, piston comprising a head'and a'slotted skirt, a slide member contacting the skirt on the inside and having anarm adjacent to the head, a screw threaded into the arm and occupying a smooth hole in the head, the screw being adjustable from above the head, and

a buffer spring having means by which its lower end is anchored to the slide member and means by which its upper end is connected with the head, causingthe head to form an abutment from which the spring exercises pressure against the slide member downwardly and outwardly.

7. In a piston having a skirt with a slot,,ex-

pander means inside of the piston comprising a means inside of the piston consisting of a slide member and a spring, adjusting means to suspend the slide member from the piston head and to adjust it along the skirt, one end of the spring being sharpened to engage the piston and the other end being notched, and a screw carried by the slide member, the point of the screw being notched to engage the notch 01 the spring.

9. In a piston having a slotted skirt, expander means inside of the piston consisting of a slide member lying against the skirt and a connected spring having its free end in engagement with the piston, and adjusting means for the slide member consisting of a flat-headed screw threaded into a part of the slide member, and a beveled opening in the pistonhead containing the screw head.

I 10. Means to expand the slotted skirt of a piston with reference to the bore of a cylinder which contains the piston and which cylinder has a hole in its head positioned within the confines of the bore, there being an annular internal corner where the head merges into the skirt, said means comprising a bowed expander, means by which one end of the expander is adapted to be anchored to the skirt adjacent to its slot, the other end of the expander being adapted to be propped in said corner, and means to adjustably secure the last means to the piston head at a place in line with the hole, said hole containing a plug which normally closes it.

11. In a piston having a slotted skirt and a head, resilient expander means within the. piston and having one portion thereof in contact with the inside part of one side of the skirt and having an end portion thereof in contact with the head, and means swivelled in the head adjustably connected with the expander.

12. In a piston having a slotted skirt and a head, there being an annular internal corner expansion slots, there being an annular comer where the head merges into the skirt, expander means within the piston, said means including a single diagonally positioned tension member having its inner end fixed practically in the corner and its outer end disposed adjacently to the skirt, and means which has a key in one 01. the slots, on which means the outer end of the tension member is fixed, both ends of said member thus being fixed.

14. Expander means adapted to go inside of a slotted skirt piston which has an annular internal corner where the head merges into the skirt, said means comprising a truss having one end adapted to be fixed practically in the corner and the other end adapted to be located adjacent to the skirt, and means adapted to be swivelled in the piston head and connected directly with said other end to positively move it in at least one direction 10 along the skirt.

15. Expander means adapted to go inside of a piston, comprising a. bowed bufler spring to have a solid abutment at one end in the piston, the othed end being adapted to exercise pressure against the skirt. and double adjusting means applied to said other end, one adjusting meansbeing capable of being worked from the head of the Piston, the other adjusting means being capable of being worked from the bottom of the piston.

.ZENO ARNO 'BRUEGGER. 

